Technical Abstract:
Twenty pigs (14-d, 5 kg) were used to determine if feeding spray-dried plasma (SDP) affects the response to a lipopolysaccharide (LPS) challenge. Pigs were allotted to one of four treatments with two levels of SDP (0 vs 7%) and one of two injections (LPS vs saline). Diets were formulated to contain equal ME and digestible essential amino acids and were fed for 7 d postweaning. On d 6, the pigs were non-surgically fitted with jugular cannulae. On d 7, i.p. injections of either saline or LPS were given, followed by blood samples at 15-min intervals for 3 hr. After 3 hr, pigs were killed, and intestinal samples were collected to measure villus height, crypt depth, and villus:crypt ratio (VCR). Spray-dried plasma did not affect weight gain. For pigs that received a saline injection, SDP decreased crypt depth (P<.05), increased VCR (P<.05), with no effect on villus height. Injecting LPS to pigs fed the no-SDP diet did not affect intestinal morphology. Injecting LPS to pigs fed the 7% SDP diet decreased villus height (P<.05) and VCR (P<.05) with no effect on crypt depth. There was an interaction between SDP and LPS for both serum ACTH (P<.001) and cortisol (P<.05). After LPS injection, pigs fed SDP had an increase in ACTH, while pigs fed no SDP had no change in ACTH. The LPS challenge raised serum cortisol levels for pigs fed both diets; however, this increase was greater for pigs fed the SDP diet than the no-SDP diet. These results indicate that SDP alters the responsiveness of the hypothalamic-pituitary-adrenal axis of young pigs following an immunological challenge. Further studies are needed to deterine if these differences in responsiveness and intestinal morphology may compromise the immune function in young pigs.